I need some advice on CRF -- Erythropoietin

My best friend has an elderly cat who was diagnosed with CRF some time ago. He has been maintaining pretty well, but it appears that he has gotten to a point where the Vet is advising that his Mom start him on a regimen of Erthropoietin. His red blood count on his most current test went from 19 to 18, so he has anemia due to the CRF. Has anyone had any experience with Epogen (which is the drug)??? Any advise would be greatly appreciated.